Cellular Physiology and Neurophysiology

SECTION I, Fundamental Physicochemical Concepts

CHAPTER 1, INTRODUCTION: HOMEOSTASIS AND CELLULAR PHYSIOLOGY

Homeostasis Enables the Body to Survive in Diverse Environments

The Body Is an Ensemble of Functionally and Spatially Distinct Compartments

Transport Processes Are Essential to Physiological Function

Cellular Physiology Focuses on Membrane-Mediated Processes and on Muscle Function

Summary

Key Words and Concepts

CHAPTER 2, DIFFUSION AND PERMEABILITY

Diffusion Is the Migration of Molecules down a Concentration Gradient

Ficks First Law of Diffusion Summarizes our Intuitive Understanding of Diffusion

Essential Aspects of Diffusion Are Revealed by Quantitative Examination of Random, Microscopic Movements of Molecules

Ficks First Law Can Be Used to Describe Diffusion across a Membrane Barrier

Summary

Key Words and Concepts

Study Problems

CHAPTER 3, OSMOTIC PRESSURE AND WATER MOVEMENT

Osmosis Is the Transport of Solvent Driven by a Difference in Solute Concentration Across a Membrane That Is Impermeable to Solute

Water Transport during Osmosis Leads to Changes in Volume

Osmotic Pressure Drives the Net Transport of Water during Osmosis

Osmotic Pressure and Hydrostatic Pressure Are Functionally Equivalent in Their Ability to Drive Water Movement Through a Membrane

Only Impermeant Solutes Can Have Permanent Osmotic Effects

Summary

Key Words and Concepts

Study Problems

CHAPTER 4, ELECTRICAL CONSEQUENCES OF IONIC GRADIENTS

Ions Are Typically Present at Different Concentrations on Opposite Sides of a Biomembrane

Selective Ionic Permeability Through Membranes Has Electrical Consequences: The Nernst Equation

The Stable Resting Membrane Potential in a Living Cell Is Established by Balancing Multiple Ionic Fluxes

The Cell Can Change Its Membrane Potential by Selectively Changing Membrane Permeability to Certain Ions

The Donnan Effect Is an Osmotic Threat to Living Cells

Summary

Key Words and Concepts

Study Problems

SECTION II, Ion Channels and Excitable Membranes

CHAPTER 5, ION CHANNELS

Ion Channels Are Critical Determinants of the Electrical Behavior of Membranes

Distinct Types of Ion Channels Have Several Common Properties

Ion Channels Share Structural Similarities and Can Be Grouped into Gene Families

Summary

Key Words and Concepts

Study Problems

CHAPTER 6, PASSIVE ELECTRICAL PROPERTIES OF MEMBRANES

The Time Course and Spread of Membrane Potential Changes Are Predicted by the Passive Electrical Properties of the Membrane

The Equivalent Circuit of a Membrane Has a Resistor in Parallel with a Capacitor

Passive Membrane Properties Produce Linear Current-Voltage Relationships

Membrane Capacitance Affects the Time Course of Voltage Changes

Membrane and Axoplasmic Resistances Affect the Passive Spread of Subthreshold Electrical Signals

Summary

Key Words and Concepts

Study Problems

CHAPTER 7, GENERATION AND PROPAGATION OF THE ACTION POTENTIAL

The Action Potential Is a Rapid and Transient Depolarization of the Membrane Potential in Electrically Excitable Cells

Ion Channel Function Is Studied with a Voltage Clamp

Individual Ion Channels Have Two Conductance Levels

Na⁺ Channels Inactivate during Maintained Depolarization

Action Potentials Are Generated by Voltage-Gated Na⁺ and K⁺ Channels

Action Potential Propagation Occurs as a Result of Local Circuit Currents

Summary

Key Words and Concepts

Study Problems

CHAPTER 8, ION CHANNEL DIVERSITY

Various Types of Ion Channels Help to Regulate Cellular Processes

Voltage-Gated Ca²⁺ Channels Contribute to Electrical Activity and Mediate Ca²⁺ Entry into Cells

Many Members of the Transient Receptor Potential Superfamily of Channels Mediate Ca²⁺ Entry

K⁺-Selective Channels Are the Most Diverse Type of Channel

Ion Channel Activity Can Be Regulated by Second-Messenger Pathways

Summary

Key Words and Concepts

Study Problems

SECTION III, Solute Transport

CHAPTER 9, ELECTROCHEMICAL POTENTIAL ENERGY AND TRANSPORT PROCESSES

Electrochemical Potential Energy Drives All Transport Processes

Summary

Key Words and Concepts

Study Problems

CHAPTER 10, PASSIVE SOLUTE TRANSPORT

Diffusion across Biological Membranes Is Limited by Lipid Solubility

Channel, Carrier, and Pump Proteins Mediate Transport across Biological Membranes

Carriers Are Integral Membrane Proteins That Open to Only One Side of the Membrane at a Time

Coupling the Transport of One Solute to the Downhill Transport of Another Solute Enables Carriers to Move the Cotransported or Countertransported Solute Uphill against an Electrochemical Gradient

Net Transport of Some Solutes across Epithelia Is Effected by Coupling Two Transport Processes in Series

Na⁺ Is Exchanged for Solutes Such as Ca²⁺ and H⁺ by Countertransport Mechanisms

Multiple Transport Systems Can Be Functionally Coupled

Summary

Key Words and Concepts

Study Problems

CHAPTER 11, ACTIVE TRANSPORT

Primary Active Transport Converts the Chemical Energy from ATP into Electrochemical Potential Energy Stored in Solute Gradients

The Plasma Membrane Na⁺ Pump (Na⁺, K⁺-ATPase) Maintains the Low Na⁺ and High K⁺ Concentrations in the Cytosol

Intracellular Ca²⁺ Signaling Is Universal and Is Closely Tied to Ca²⁺ Homeostasis

Several Other Plasma Membrane Transport ATPases Are Physiologically Important

Net Transport across Epithelial Cells Depends on the Coupling of Apical and Basolateral Membrane Transport Systems

Summary

Key Words and Concepts

Study Problems

SECTION IV, Physiology of Synaptic Transmission

CHAPTER 12, SYNAPTIC PHYSIOLOGY I

The Synapse Is a Junction Between Cells That Is Specialized for Cell-Cell Signaling

Neurons Communicate with Other Neurons and with Muscle by Releasing Neurotransmitters

The Synaptic Vesicle Cycle Is a Precisely Choreographed Process for Delivering Neurotransmitter into the Synaptic Cleft

Short-Term Synaptic Plasticity Is a Transient, Use-Dependent Change in the Efficacy of Synaptic Transmission

Summary

Key Words and Concepts

Study Problems

CHAPTER 13, SYNAPTIC PHYSIOLOGY II

Chemical Synapses Afford Specificity, Variety, and Fine Tuning of Neurotransmission

Receptors Mediate the Actions of Neurotransmitters in Postsynaptic Cells

Acetylcholine Receptors Can Be Ionotropic or Metabotropic

Amino Acid Neurotransmitters Mediate Many Excitatory and Inhibitory Responses in the Brain

Neurotransmitters That Bind to Ionotropic Receptors Cause Membrane Conductance Changes

Biogenic Amines, Purines, and Neuropeptides Are Important Classes of Transmitters with a Wide Spectrum of Actions

Unconventional Neurotransmitters Modulate Many Complex Physiological Responses

Long-Term Synaptic Potentiation and Depression Are Persistent Changes in the Efficacy of Synaptic Transmission Induced by Neural Activity

Summary

Key Words and Concepts

Study Problems

SECTION V, Molecular Motors and Muscle Contraction

CHAPTER 14, MOLECULAR MOTORS AND THE MECHANISM OF MUSCLE CONTRACTION

Molecular Motors Produce Movement by Converting Chemical Energy into Kinetic Energy

Single Skeletal Muscle Fibers Are Composed of Many Myofibrils

The Sarcomere Is the Basic Unit of Contraction in Skeletal Muscle

Muscle Contraction Results from Thick and Thin Filaments Sliding Past Each Other (The Sliding Filament Mechanism)

The Cross-Bridge Cycle Powers Muscle Contraction

In Skeletal and Cardiac Muscles, Ca²⁺ Activates Contraction by Binding to the Regulatory Protein Troponin C

The Structure and Function of Cardiac Muscle and Smooth Muscle Are Distinctly Different from Those of Skeletal Muscle

Summary

Key Words and Concepts

Study Problems

CHAPTER 15, EXCITATION-CONTRACTION COUPLING IN MUSCLE

Skeletal Muscle Contraction Is Initiated by a Depolarization of the Surface Membrane

Direct Mechanical Interaction Between Sarcolemmal and Sarcoplasmic Reticulum Membrane Proteins Mediates Excitation-Contraction Coupling in Skeletal Muscle

Ca²⁺-Induced Ca²⁺ Release Is Central to Excitation-Contraction Coupling in Cardiac MuscleSmooth Muscle Excitation-Contraction Coupling Is Fundamentally Different from That in Skeletal and Cardiac Muscles

Summary

Key Words and Concepts

Study Problems

CHAPTER 16, MECHANICS OF MUSCLE CONTRACTION

The Total Force Generated by a Skeletal Muscle Can Be Varied

Skeletal Muscle Mechanics Is Characterized by Two Fundamental Relationships

There Are Three Types of Skeletal Muscle Motor Units

The Force Generated by Cardiac Muscle Is Regulated by Mechanisms That Control Intracellular Ca²⁺

Mechanical Properties of Cardiac and Skeletal Muscle Are Similar but Quantitatively Different

Dynamics of Smooth Muscle Contraction Differ Markedly from Those of Skeletal and Cardiac Muscle

The Relationships among Intracellular Ca²⁺, Myosin Light Chain Phosphorylation, and Force in Smooth Muscles Is Complex

Summary

Key Words and Concepts

Study Problems

SEction VI Epilogue and Appendicies

EPILOGUE

APPENDIX A, ABBREVIATIONS, SYMBOLS, AND NUMERICAL CONSTANTS

Abbreviations

Symbols

Numerical Constants

APPENDIX B, A MATHEMATICAL REFRESHER

Exponents

Logarithms

Solving Quadratic Equations

Differentiation and Derivatives

Integration: The Antiderivative and the Definite Integral

Differential Equations

APPENDIX C, ROOT-MEAN-SQUARED DISPLACEMENT OF DIFFUSING MOLECULES

APPENDIX D, SUMMARY OF ELEMENTARY CIRCUIT THEORY

Cell Membranes Are Modeled with Electrical Circuits

Definitions of Electrical Parameters

Current Flow in Simple Circuits

APPENDIX E, ANSWERS TO STUDY PROBLEMS

APPENDIX F, REVIEW EXAMINATION

Answers to Review Examination